​One seller learned that lesson the hard way last April, when Immigration and Customs Enforcement agents in Miami spotted protected Peruvian artifacts on the site and launched an investigation.

Turns out the seller, whom the feds haven't identified, had five terracotta vases and vessels from Peru's Nazca Region and elsewhere, all more than 1,000 years old.

ICE confiscated the artifacts, and earlier today, Miami agents returned them to Peru, says Barbara Gonzalez, an ICE spokeswoman.

The case doesn't come close to the size and scope of a scheme cooked up by the Aviles family, which we wrote about a couple years ago. Cecilia Marcillo-Aviles and her daughter, Susan, tried to peddle more than 160 ancient Peruvian relics -- some more than 6,000 years old -- from their Coral Gables home.

But it does show that the illegal art trade is alive and well in Miami. Today's case also reinforces how hard it is to hit underground traders with stiff sentences.

Marcillo-Aviles and her daughter both got off the hook with a $600 fine back in 2008.

And the eBay seller wasn't charged criminally for peddling the artifacts, Gonzalez says.